The present invention relates to telecommunications devices and techniques. More particularly, the present invention provides a technique including an apparatus for transmitting information using a TCP connection over a satellite system for use in a wide area network of computers such as the Internet. The present apparatus provides a high speed and quality transmission of signals to a distant location over a satellite system using an Xpress Transport Protocol (herein “XTP”) protocol, for example. But it will be recognized that the invention has a much wider range of applicability; it can also be applied to a private bridged network, terrestrial wireless network links, and the like.
The Internet is an international “super-network” connecting together millions of individual computer networks and computers. The Internet is generally not a single entity. It is an extremely diffuse and complex system over which no single entity has complete authority or control. Although the Internet is widely known for one of its ways of presenting information through the World Wide Web (herein “Web”), there are many other services currently available based upon the general Internet protocols and infrastructure.
The Web is generally easy to use for people inexperienced with computers. Information on the Web can be presented on “pages” of graphics and text that contain “links” to other pages either within the same set of data files (i.e., Web site) or within data files located on other computer networks. Users often access information on the Web using a “browser” program such as one made by Netscape Communications Corporation of Mountain View, Calif. or Microsoft Corporation of Redmond, Wash. Browser programs process information from Web sites and display the information using graphics, text, sound, and animation. Accordingly, the Web has become a popular medium for advertising goods and services directly to consumers.
The Internet supports many other forms of communication. For example, the Internet allows one-to-one communication via electronic mail, which is commonly known as “e-mail.” The Internet also has “bulletin boards” which are used by users to post colorful text and graphics for others to read and respond to. For real time communication, the Internet has “chat rooms” and the like, which allow users to communicate to each other by way of typed messages. In some cases, the Internet can also be used for voice communication between users. All of these forms of communication are possible, at least in part, by way of an important connection, which allows information to be transmitted from many different servers on the Internet.
The Internet is based on the TCP/IP protocol suite. At the network layer, and Internet Protocol, which is known as IP, provides a mechanism to deliver packets addressed to individual computers. The Internet has a plurality of computer systems implementing IP, which are generally interconnected to each other using local area networks and dedicated transmission lines to form a wide area network of computers. IP packets are delivered on a best effort basis and are not guaranteed to arrive at their intended destination, which is known as “unreliable” service.
For many applications that require reliable data delivery service, the Internet uses a connection mechanism called Transmission Control Protocol, which is known as TCP. TCP has a variety of desirable characteristics that allows it to be suitable for communication over the Internet. For example, TCP considers the data size or best sized segment of data to send from a transmitting server over the communication medium to a receiving server. Additionally, TCP maintains a timer, which waits for the receiving server to send an acknowledgement of the reception of the data segment from the transmitting server. If the timer times out before the acknowledgement is received, TCP resends the data segment, which provides reliability in the communication. TCP also maintains a checksum on its header and data, which monitors any modification in the data in transit. If the data arrives with an invalid checksum, TCP discards the data and does not acknowledge receiving the data. If data segments arrive out of order, TCP can also recombine the segments in order at the receiving server. Furthermore, TCP provides flow control, which only allows a finite amount of data to be sent to a buffer on the receiving server. This prevents a fast server computer from overflowing all the buffers on a slower server computer.
Although TCP has been well suited for transmitting Internet data between a plurality of servers, which are coupled to each other by way of conventional telephone systems and lines with similar characteristics, TCP has many limitations. For example, TCP is suitable for “short hops” but often slows down communication over extremely long distances which can have significant latency (e.g., transcontinental hops via satellite). Here, the flow control and acknowledgement features take too long to send and receive, which make communication slow. Additionally, opportunities for gains in efficiency still exist. In particular, TCP has been found to be slow and cumbersome for transmission of Internet data over a satellite network, for example. Additionally, networking using satellite often encounters significant bit error rates, which leads to further slowing of TCP connections. These and other limitations will be more fully described according to the Figs. below.
From the above, it is seen that a more efficient way of transporting Internet services over large geographical regions using wireless communication media is highly desirable.